I/GCSE Biology - Evolution

In this post, we'll talk about the evolution in I/GCSE Biology. Let's get started! 😆

Biologists can measure changes in the environment by using indicators. These may be NON-LIVING or LIVING.

1. NON – LIVING INDICATORS:

• Nitrate levels can be measured using test kits with chemicals that change colour. The chemicals can then be matched against a chart indicating the amount of nitrate present in the sample
• Temperature can be measured using a thermometer, or a data-logger, which is more accurate and reliable
• Carbon dioxide levels can be measured using data-loggers

2. BIOLOGICAL INDICATIORS:

• In the oceans, phytoplankton (plant) are useful for detecting the effect of temperature changes and for detecting changes in the food web
• Lichens grow very slowly and are vulnerable to atmospheric pollutants and acid rain. A decline in their number can indicate pollution
• River organisms, such as the larvae of mayfly (mayfly nymphs) can be used to indicate the quality of water. Mayfly nymphs can only live in clean river water with enough oxygen water. If a river has mayfly nymphs, then pollution levels will be low

• Life on Earth began around 3500 million years ago.
• ALL life on Earth, including all life that is now extinct, evolved from very simple living things - so all organisms share a common ancestor.
• However there is variation between individuals of the same species and some of this variation is genetic so can be passed on to offspring.

• Genetic variation is caused when changes called MUTATIONS take place in the genes.
• These changes are random and can be caused by background radiation and chemicals.
• MUTATIONS cause different proteins to be produces and this changes the function of the gene.
• If the mutations occur in the cells producing eggs in the ovaries and sperm in the testes, then the mutated genes may be passed on to the offspring.
• Sometimes the mutation causes new characteristics.

In I/GCSE Biology, The following points are commonly asked in the exam!!!

The genetic variation between individuals in a species means:

• those with characteristics that improve their chances of survival in their physical environment are more likely to live to adulthood.
• When these individuals reproduce, they pass on the beneficial characteristics to their offspring.

• Where animals and plants with certain traits are deliberately mated together to produce offspring with certain desirable characteristics.
• This could be used to create new varieties of organisms or to increase the yield of animals and plants.

And we're done with this topic! Well Done!

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Drafted by Alyssa (Biology)

References:

1. "Pollution Noadswood Science", https://slideplayer.com/slide/5818742/18/images/21/Non-Living+Indicators.jpg
2. "Lichens as Bioindicators", https://www.nps.gov/articles/images/5474697003_ba1b9a17fe_b.jpg?maxwidth=650&autorotate=false
3. "Geological Time Scale", https://lh3.googleusercontent.com/proxy/m9jvWQAsqHBKPc_UTOElbC-4TeAYhYHhSk2FdDlKipcwcKJ-somwUtmTMX1blgukoVbQrDSnxSFH3BY-MrMsUINLl-lg6K2SpsTNjyax7jiNsPq2p0c_FYx0OOE57g6PqU0iNIREeS0k
4. "29 Best 15 for 15: Human Genomic Variation ideas", https://i.pinimg.com/originals/9e/ee/e4/9eeee4b67ef1f7a159b13833553bfb0d.jpg
5. "Natural Selection in Caribou", https://www.exploringnature.org/graphics/posters/natural_section_caribou_diagram72.jpg
6. "Selective Breeding", https://storage.googleapis.com/climate-science.appspot.com/en-v5/C1_2-Details-2-selective_breeding.png